Two Mountains: Tadasana versus Samasthiti

So what is the difference between Tadasana and Samasthiti?

In its simpilist terms Tadasana is a pose while Samasthiti is a command of attention. Looking at the roots it becomes quite clear. Tadasana (tada = mountain / asana = pose) translates to Mountain Pose, while Samasthiti (sama = same, equal / sthiti = to establish, to stand) translates to establishing an equal and steady stance.

So if you hear a teacher say Samasthiti while you are standing in Tadasana, recognize what they are asking you to do is bring your attention to your stance and establish a firm and equal stance!